The Morris water maze is the rodent equivalent of an I.Q. test: mice are placed in a tank filled with water dyed an opaque color. Beneath a small area of the surface is a platform, which the mice can’t see. [See two-minute video below.]

Despite what you’ve heard about rodents and sinking ships, mice hate water; those that blunder upon the platform climb onto it immediately. Scientists have long agreed that a mouse’s spatial memory can be inferred by how quickly the animal finds its way in subsequent dunkings. A “smart” mouse remembers the platform and swims right to it.

In the late 1990s, one group of mice at the Salk Institute for Biological Studies, near San Diego, blew away the others in the Morris maze. The difference between the smart mice and those that floundered? Exercise. The brainy mice had running wheels in their cages, and the others didn’t.

Scientists have suspected for decades that exercise, particularly regular aerobic exercise, can affect the brain. But they could only speculate as to how. Now an expanding body of research shows that exercise can improve the performance of the brain by boosting memory and cognitive processing speed. Exercise can, in fact, create a stronger, faster brain.

This theory emerged from those mouse studies at the Salk Institute. After conducting maze tests, the neuroscientist Fred H. Gage and his colleagues examined brain samples from the mice. Conventional wisdom had long held that animal (and human) brains weren’t malleable: after a brief window early in life, the brain could no longer grow or renew itself. . . .

All of the mice showed this vivid proof of what’s known as “neurogenesis,” or the creation of new neurons. But the brains of the athletic mice in particular showed many more. These mice, the ones that scampered on running wheels, were producing two to three times as many new neurons as the mice that didn’t exercise.

* * *

Gage’s discovery hit the world of neurological research like a thunderclap. Since then, scientists have been finding more evidence that the human brain is not only capable of renewing itself but that exercise speeds the process.

“We’ve always known that our brains control our behavior,” Gage says, “but not that our behavior could control and change the structure of our brains.”

* * *

This spring, neuroscientists at Columbia University in New York City published a study in which a group of men and women, ranging in age from 21 to 45, began working out for one hour four times a week. After 12 weeks, the test subjects, predictably, became more fit. . . .

But something else happened as a result of all those workouts: blood flowed at a much higher volume to a part of the brain responsible for neurogenesis. Functional M.R.I.’s showed that a portion of each person’s hippocampus received almost twice the blood volume as it did before. Scientists suspect that the blood pumping into that part of the brain was helping to produce fresh neurons.

The hippocampus plays a large role in how mammals create and process memories; it also plays a role in cognition. [For more technical details, view the two-minute video above.] If your hippocampus is damaged, you most likely have trouble learning facts and forming new memories. Age plays a factor, too. As you get older, your brain gets smaller, and one of the areas most prone to this shrinkage is the hippocampus. (This can start depressingly early, in your 30’s.) . . . .

The Columbia study suggests that shrinkage to parts of the hippocampus can be slowed via exercise. The subjects showed significant improvements in memory, as measured by a word-recall test. Those with the biggest increases in VO2 max had the best scores of all.

“It’s reasonable to infer, though we’re not yet certain, that neurogenesis was happening in the people’s hippocampi,” says Scott A. Small, an associate professor of neurology at Columbia and the senior author of the study, “and that working out was driving the neurogenesis.”

Other recent studies support this theory. . . . These results raise the hope that the human brain has the capacity not only to produce new cells but also to add new blood vessels and strengthen neural connections, allowing young neurons to integrate themselves into the wider neural network. . . .

And the benefits aren’t limited to adults. Other University of Illinois scientists have studied school-age children and found that those who have a higher level of aerobic fitness processed information more efficiently; they were quicker on a battery of computerized flashcard tests. The researchers also found that higher levels of aerobic fitness corresponded to better standardized test scores among a set of Illinois public school students. . . .

What is it about exercise that prompts the brain to remake itself? Different scientists have pet theories. . . .

. . . [Some] researchers are looking at the role of serotonin, a hormone that influences mood. Exercise speeds the brain’s production of serotonin, which could, in turn, prompt new neurons to grow. Abnormally low levels of serotonin have been associated with clinical depression, as has a strikingly shrunken hippocampus. Many antidepressant medications, like Prozac, increase the effectiveness of serotonin. Interestingly, these drugs take three to four weeks to begin working — about the same time required for new neurons to form and mature. Part of the reason these drugs are effective, then, could be that they’re increasing neurogenesis. “Just as exercise does,”Gage says.

Gage, by the way, exercises just about every day, as do most colleagues in his field. Scott Small at Columbia, for instance , likes nothing better than a strenuous game of tennis. “As a neurologist,” he explains, “I constantly get asked at cocktail parties what someone can do to protect their mental functioning. I tell them, ‘Put down that glass and go for a run.’ ”

* * *

Thanks to Situationist reader, Vaughan Stewart, for alerting us to this story. To read the the entire article, click here. For an earlier Situationist post discussing the role of “mindset” on exercise, go to “January Fool’s Day.”

2 Responses to “Brainicize: The Situational Malleability of our Brains”

Excellent post! Its interesting, in health care, we always noticed that the seniors who were more active seemed to have a natural immune system build in as well as an ability to have better cognitive function.